Structure And Application Analysis Of Lead-acid Battery


Lead-acid batteries are usually composed of 3 or 6 single-cell batteries in series, consisting of a plate, a separator, an electrolyte, a shell, a pole and a liquid filling port plug (none for maintenance-free batteries).

Lead-acid battery

1. Lead acid battery plate

The plate is divided into positive plate and negative plate, which are composed of grid frame and active material.

The purpose of grid frame

The ladder has a side use, will accelerate the precipitation of hydrogen and accelerate electrolyte consumption, but also easy to introduce from the positive plate grid frame caused by battery self-discharge and grid frame corrosion, shorten the service life of the storage. At present, low brocade alloy grid frame (containing ladder of 2%-3.5%) or lead-calcium alloy is used as grid frame at home and abroad.

The active material on the positive plate is lead dioxide (Pb02), which is dark brown; The active substance on the negative plate is pure lead (Pb) in the form of sponge, which is bluish gray. The active material is prepared into a paste and filled in the gap of the grid frame and dried to form a plate.

The positive and negative plates are immersed in the electrolyte, and the electromotive force of about 2V can be obtained. In order to increase the capacity of the battery, a plurality of positive and negative plates are connected in parallel to form a positive and negative plate group. In each single cell battery, the number of positive plates is less than the negative plate, so that each positive plate is in between the two negative plates, can make the positive plate on both sides of the discharge average, alert for uneven discharge caused by plate arch.

2. Separator for lead-acid batteries

The baffle is inserted between the positive and negative plates, which is used to prevent short circuit caused by contact between the positive and negative plates. The separator should be acid resistant and porous to facilitate the penetration of the electrolyte. The commonly used partition materials are wood, microporous rubber and microporous plastic, etc. Among them, wood separator acid resistance is poor, and has been eliminated. Microporous rubber clapboard has the best performance but high cost. Microporous plastic clapboard has small pore size, high porosity and low cost, so it is widely used.

In the installation with the groove side should be toward the positive plate, and vertical to the bottom of the shell. At the same time, the groove can make the electrolyte up and down dredging, so that bubbles can rise along the groove, microporous plastic can be made into a bag partition, it can be set on the positive plate can alert active material off.

3. The electrolyte

In the chemical reaction of lead-acid battery, electrolyte plays the role of conducting between ions, and participates in the chemical reaction of battery. The electrolyte is made of pure sulfuric acid (H: S0.) and distilled water in a certain proportion, and its density is generally 1.24~1.30g/cm’. Select electrolyte density according to season and region. The liquid level should be 10-15mm higher than the upper plane of the plate (separator).

4.  Shell of lead-acid battery

The shell is used to hold the electrolyte and the plate group and shall be resistant to acid, heat and shock. The shell is made of hard rubber or polypropylene plastic. It is an integral structure with a raised ribs at the bottom to use the plate group. The interior of the shell is divided into three or six unconnected single compartments by the interwalls, which are connected in series with lead mass connective strips. The upper part of the shell is sealed with a battery cover of the same material, which is equipped with a filling hole corresponding to each single cell for adding electrolyte and distilled water, as well as for measuring electrolyte density, temperature and liquid level height. The vent hole on the cover of the liquid filling hole enables the gas in the chemical reaction of the battery to be discharged smoothly.

5. Pole of lead-acid battery

There are three kinds of terminals welded on the horizontal plate of the head and tail bipolar plate group of the general battery, namely, terminal post side control type, conical type and working type. For the convenience of difference, the positive terminal post is marked with + or P mark, some terminals are painted with red paint, and the negative terminal post is marked with - or N mark. When the discrimination is not clear, the voltmeter can be used to measure.